1. Field of Invention
The present invention relates to a system for stock rotation of liquids, such as soft drink syrups, contained in collapsible bag-type reservoirs or replaceable packages. More specifically, the present invention relates to an automatic change-over device for automatically switching between a primary supply reservoir and a secondary supply reservoir in response to an empty condition of the primary reservoir.
2. Description of Prior Art
Heretofore the stock rotation or changing of liquid bag packages such as milk, soft drink syrups or chemicals, has been accomplished by manual methods. When a package became empty the pump system was not supplied with liquid until the packages could be manually changed. This caused unavoidable, unexpected and inconvenient delays in the dispensing operation. To provide for larger reserves many prior art systems connected packages in a parallel arrangement. This does not provide for the necessary stock rotation required by many perishable food items such as milk and soft drink syrups. By contrast, rigid types of sealed packages have inlet and outlet openings and are often connected in series. These too do not provide complete rotation of liquid products since mixing occurs. If bag packages were connected in series they would not provide for reserve capacity but only a large initial capacity, since the packages will collapse equally unless assisted by gravity or other external means.
Automatic change-over devices for non-viscous liquids disposed in open or vented rigid containers are known in the art. However, these devices are not satisfactory for automatic stock rotation of viscous liquids contained in flexible bag packages. Furthermore, many liquids tend to crystalize when exposed to air in open systems further complicating container rotation. Bag packages create a sealed and closed system to air and other outside contaminates.
For example, an automatic change-over system for gas contained in a primary and secondary bank of storage tanks is disclosed in U.S. Pat. No. 2,968,162 to Acomb issued Jan. 17, 1961. The Acomb system effects a change-over from one group of supply tanks to another in response to pressure changes caused by an empty condition of the tanks being dispensed. However, the Acomb system does not possess the necessary sensitivity to automatically dispense more viscous liquids, such as syrups, in a fast and reliable manner.
Another similar type of automatic change-over system is disclosed in U.S. Pat. No. 3,825,027 to Henderson. In the Henderson system, the change-over sensitivity is enhanced by the provision of ball float valves 34, 36 in the respective primary and secondary supply circuits. The Henderson system works very well for dispensing liquid fuels of low viscosity, this being the purpose for which it was designed. However, the float valves tend to stick due to sugar build-up when the liquid being dispensed is a viscous liquid such as soft drink syrups.